My former vet (moved on to small animal ) was also a chiropractor. I asked about whether I should have him adjust my horse. He watched her move. He ran hands over her. “There is nothing to adjust. I don’t need to take your money for doing nothing. I will absolutely adjust her if there is ever anything to do.”
So, if you’re wanting to have it done just to make yourself feel better - save your money or even better, spend it on a fabulous massage therapist who understands your sport and will not just make pony feel better but will help you figure out exercises for loosening/strengthening problem areas. THAT is money well spent - some of the best training assistance I’ve ever received has come from my horse’s REMT
For instance, X needs to be stronger in order to allow Y to relax and stretch. This limb/neck/pelvis needs to move in this direction to do that. Then we’d discuss how she wanted the horse to move and which exercises (from galloping to travers) would best accomplish it.
Editing to add that she WILL call me out for going too far in one direction or another which is also a great training aid. “You’ve been doing too much collection and not enough stretching” or “You’re collection is not currently 100% through because X,Y, and Z muscles are overdeveloped right now.” And we will discuss and come up with a list of tasks/exercises to fix whatever I’ve inadvertently wrecked. Worth her weight in gold!